WorkStruct: Merge the pending bit into the wq_data pointer
Reclaim a word from the size of the work_struct by folding the pending bit and
the wq_data pointer together. This shouldn't cause misalignment problems as
all pointers should be at least 4-byte aligned.
Signed-Off-By: David Howells <dhowells@redhat.com>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 1e9d61e..9674797 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -80,6 +80,29 @@
return list_empty(&wq->list);
}
+static inline void set_wq_data(struct work_struct *work, void *wq)
+{
+ unsigned long new, old, res;
+
+ /* assume the pending flag is already set and that the task has already
+ * been queued on this workqueue */
+ new = (unsigned long) wq | (1UL << WORK_STRUCT_PENDING);
+ res = work->management;
+ if (res != new) {
+ do {
+ old = res;
+ new = (unsigned long) wq;
+ new |= (old & WORK_STRUCT_FLAG_MASK);
+ res = cmpxchg(&work->management, old, new);
+ } while (res != old);
+ }
+}
+
+static inline void *get_wq_data(struct work_struct *work)
+{
+ return (void *) (work->management & WORK_STRUCT_WQ_DATA_MASK);
+}
+
/* Preempt must be disabled. */
static void __queue_work(struct cpu_workqueue_struct *cwq,
struct work_struct *work)
@@ -87,7 +110,7 @@
unsigned long flags;
spin_lock_irqsave(&cwq->lock, flags);
- work->wq_data = cwq;
+ set_wq_data(work, cwq);
list_add_tail(&work->entry, &cwq->worklist);
cwq->insert_sequence++;
wake_up(&cwq->more_work);
@@ -108,7 +131,7 @@
{
int ret = 0, cpu = get_cpu();
- if (!test_and_set_bit(0, &work->pending)) {
+ if (!test_and_set_bit(WORK_STRUCT_PENDING, &work->management)) {
if (unlikely(is_single_threaded(wq)))
cpu = singlethread_cpu;
BUG_ON(!list_empty(&work->entry));
@@ -123,7 +146,7 @@
static void delayed_work_timer_fn(unsigned long __data)
{
struct delayed_work *dwork = (struct delayed_work *)__data;
- struct workqueue_struct *wq = dwork->work.wq_data;
+ struct workqueue_struct *wq = get_wq_data(&dwork->work);
int cpu = smp_processor_id();
if (unlikely(is_single_threaded(wq)))
@@ -150,12 +173,12 @@
if (delay == 0)
return queue_work(wq, work);
- if (!test_and_set_bit(0, &work->pending)) {
+ if (!test_and_set_bit(WORK_STRUCT_PENDING, &work->management)) {
BUG_ON(timer_pending(timer));
BUG_ON(!list_empty(&work->entry));
/* This stores wq for the moment, for the timer_fn */
- work->wq_data = wq;
+ set_wq_data(work, wq);
timer->expires = jiffies + delay;
timer->data = (unsigned long)dwork;
timer->function = delayed_work_timer_fn;
@@ -182,12 +205,12 @@
struct timer_list *timer = &dwork->timer;
struct work_struct *work = &dwork->work;
- if (!test_and_set_bit(0, &work->pending)) {
+ if (!test_and_set_bit(WORK_STRUCT_PENDING, &work->management)) {
BUG_ON(timer_pending(timer));
BUG_ON(!list_empty(&work->entry));
/* This stores wq for the moment, for the timer_fn */
- work->wq_data = wq;
+ set_wq_data(work, wq);
timer->expires = jiffies + delay;
timer->data = (unsigned long)dwork;
timer->function = delayed_work_timer_fn;
@@ -223,8 +246,8 @@
list_del_init(cwq->worklist.next);
spin_unlock_irqrestore(&cwq->lock, flags);
- BUG_ON(work->wq_data != cwq);
- clear_bit(0, &work->pending);
+ BUG_ON(get_wq_data(work) != cwq);
+ clear_bit(WORK_STRUCT_PENDING, &work->management);
f(data);
spin_lock_irqsave(&cwq->lock, flags);